Presently, optical spectroscopy may be used in some applications to serve as a diagnostic tool to detect various diseases. Notably, optical spectroscopy is sensitive to a number of biological scatterers, absorbers and fluorophores that exist in tissue. Absorbers include hemoglobin, adipose, water, beta carotene and melanin and other proteins. Scatterers include cellular and subcellular organelles. Fluorophores include metabolic electron carriers and structural proteins. Namely, these biological scatterers, absorbers, and fluorophores may be used to indicate the existence of certain diseases. Optical spectroscopy can therefore be used to provide early diagnosis of diseases, such as Alzheimer's disease, cardiovascular disease, breast cancer, and the like. The use of such technology for early detection of diseases is invaluable. For example, each year in the United States, numerous women are diagnosed with breast cancer. While this disease takes many lives, the likelihood of survival is greatly increased with early treatment of abnormalities that are discovered via breast examinations and mammograms.
In the field of breast cancer diagnosis, current methods for determining whether an abnormality is cancerous include performing an open surgical biopsy or a needle biopsy. Of the two, needle biopsy is less invasive, faster, less expensive, and requires a shorter recovery time. However, there are drawbacks to the needle biopsy procedure due to the limited sampling accuracy associated with the technique. Because only a few samples of tissue are taken from the abnormality, the possibility that a biopsy will either provide a false negative or will be inconclusive (and require a repeat biopsy) exists.
One solution to overcome these shortcomings is to utilize optical spectroscopy to probe the abnormality. Namely, research has been conducted that indicates that ultra violet-visible-near infrared (UV-VIS-NIR) spectroscopic methods show distinct differences between the spectra of normal, benign, and malignant tissues. For example, various fluorescence studies have investigated the fluorescence emission and excitation spectra to differentiate malignant tissue from benign and some normal tissue in the breast. Other studies have used fluorescence to strictly differentiate between malignant and normal fibrous tissues. While fluorescence has been used to identify several types of breast tissue, it is difficult to distinguish malignant tissues from benign tissues using fluorescence alone.
One way to compensate for the deficiency in fluorescence techniques is to use diffuse reflectance spectroscopy. Diffuse reflectance spectroscopy (e.g., visible (400-600 nm) and VIS-NIR (650-1000 nm)) takes advantage of the non-fluorescent absorbers and scatterers in breast tissue to distinguish between benign tissues and malignant tissues. Past studies have demonstrated that diffuse reflectance spectra can be measured during breast cancer surgery to identify malignant and normal tissues.
Recently, researchers have investigated the use of fluorescence spectra and diffuse reflectance spectra in combination to diagnose breast cancer ex vivo. From these studies, researchers discovered that the diffuse reflectance spectra coupled with the fluorescence emission spectra provided for distinguishing between malignant and nonmalignant tissues. Additionally, other studies have utilized a fiber optic probe to take fluorescence and diffuse reflectance spectra for the investigation of ex vivo breast tissue samples.
Despite the advances in the area of optical spectroscopy, there still remains a need for an effective method and apparatus for an in vivo optical probe that combines fluorescence and diffuse reflectance spectroscopy to improve biopsy procedures. Difficulties involved with providing an optical probe access to the tumor, form factor considerations, and the like have presented problems that hinder the implementation of such medical devices or methods. These difficulties may also present obstacles for other applications of optical spectroscopy in the medical arena, such as diagnostic monitoring, therapeutic monitoring, drug discovery and analysis, tissue oxygenation monitoring in surgical procedures, and the like.
Thus, there remains a need for an improved system and method for conducting spectral analysis of a tissue mass using an insertable instrument, an optical probe, and a Monte Carlo or diffusion algorithm.